Several studies have examined what has become known as the “July Effect”—the concern that patient outcomes may be affected when new medical residents begin training at teaching hospitals each summer.
A study published in the Journal of General Internal Medicine (2010;25:774-779) found that mortality rates in teaching hospitals were approximately 10% higher in July than during other months. The researchers suggested that the increase was more closely related to medication prescribing errors than to mistakes made during surgery itself.
Since that study was published, additional research has produced mixed results. Some studies have found evidence of a July Effect, while others have found little or no increase in adverse outcomes, likely reflecting improvements in supervision, standardized training, and patient safety systems. Even so, teaching hospitals continue to place special emphasis on close supervision of new residents during the early months of training.
